Dispensing valves for collapsible tubes and squeeze bottles containing viscous products have been the subject of much experimentation as shown by various patents.
Such experimentation has followed the fundamental concept of an upstanding projection having a tip forming a valve seat, stationarily mounted by spokes or the like radiating from the projection's bottom to a rim fixed in one way or another to a collapsible tube or squeeze bottle mouth. Above the projection an elastically deflectable diaphragm is peripherally mounted by the rim, has a hole fitting the valve head more or less, and otherwise closes the space between the projection and rim. Product pressure moves the diaphragm from the projection for dispensing the product.
The above concept does not permit a viscous product such as hair shampoo, ketchup, etc., to be squeezed from the interacting valve parts for effective and prompt valve closing. The product clings to the projection and cannot flow from the valve seat promptly. If the diaphragm is strongly elastically biased to closing position, the normal user cannot squeeze the collapsible container adequately to obtain a valve-opening product pressure. To squeeze a viscous material from between mating surfaces of a valve using that fundamental concept, requires great pressure.
The 1929 Proctor U.S. Pat. No. 1,709,948 apparently started that concept, it disclosing a stationary upward projection having a top forming a semispherical seating member or valve head on which a diaphragm having a circumferential outer peripheral rib or corrugation seats via a centrally disposed opening.
This concept of an upwardly extending projection is repeated in an exaggerated form by the 1953 Schlocksupp U.S. Pat. No. 2,628,004. Here the diaphragm is designed to transmit linear motion to the part of the diaphragm having the hole working on the projection's top end.
The 1929 Proctor patent concept is repeated in the 1976 Clark U.S. Pat. No. 3,984,035, excepting that the stationary semispherical seating member is projected upwardly even further from its mounting means.
The Nilson U.S. Pat. Nos. 3,981,419 and 4,061,254, respectively issued in 1976 and 1977, provide further examples of the stationary valve head being formed as an upwardly projecting member.
To overcome the problem of a viscous product remaining between the fixed and movable surfaces of a dispensing valve, the present inventor, in his 1977 U.S. Pat. No. 4,057,177, discloses a dispensing valve for a squeeze bottle containing a viscous product, which features a sleeve valve actuation. Using a fixed valve head projection, and here again a projection was used, a diaphragm which is deflected by product pressure resulting from squeeze bottle finger squeezing, operates a sleeve valve which upon retraction from its open position has the characteristics of, in effect, shaving off viscous material from the relatively moving parts so that positive valve closing operation is effected.